1. Field of the Invention
The present invention relates to multilayer dielectric mirrors and, more particularly pertains to a new and improved multilayer dielectric laser mirror having a garnet substrate and a method for making such a mirror.
2. Description of the Prior Art
Multilayer dielectric mirrors have long been used in lasers and for other applications because of their high reflectivity. Commonly, such mirrors have included a substrate of fused silica or glass. A mirror coating comprising a plurality of layers of selected dielectric materials is deposited on a polished surface of the substrate. Mirror substrates of fused silica or glass have most commonly been polished by optical (or mechanical) polishing techniques.
Inhomogenities in the dielectric layers of the mirror coating on such prior art laser mirrors have caused difficulties in some applications. For example, a cause of phase locking in ring laser gyros is believed to be back scattering from inhomogeneities in the laser mirrors used in these gyros.
Garnet substrates such as those which are discussed hereinafter are known and have been used, for example, in magnetic bubble memories. The polishing of these garnet substrates by chemical-mechanical techniques is well known to those skilled in the art.